No abstract

Rural domestic wastewater (RDW), one of the non-point pollution sources, has become a significant object related to sanitation improvement and water pollution control in Taihu Lake Basin, China. Current research on RDW characteristics and management with source separation is limited. In this study, a source-separated investigation into the characteristics of RDW was conducted, and the management suggestions were proposed. The results showed that the average RDW production coefficient was 94.1 ± 31.6 (range: 71.8–143.0) L/(cap·d). Household-level wastewater generation peaked two or three times daily, and the synchronous fluctuation could cause hydraulic loading shocks to treatment facilities. The population equivalent of chemical oxygen demand (COD), ammonium nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) in RDW were 78.7, 3.7, 4.12, and 0.8 g/(cap·d), respectively. Blackwater (BW) from water closet (WC) source accounted for 30.4% of the total wastewater amount, contributing 93.0%, 81.7%, and 67.3% to loads of NH4+-N, TN, and TP, respectively. Greywater (GW) from the other sources with low nutrient-related pollutant concentrations and loads, accounting for 69.6% of the total wastewater amount, was a considerable alternative water resource. The quantitative and qualitative characteristics indicated that GW and BW had the potential of being reused of water and nutrients, respectively.

Soil cracks are one of the most important physical properties of soil. The formation of soil cracks is a result of interactions between the inner and external conditions of soil. Specifically, the inner conditions include physical and chemical properties of soil, and the external conditions refer to natural and anthropogenic factors. Previous studies of soil cracks mainly focus on the soil properties and the natural environment (NE), such as soil cracks produced by biotic and abiotic processes. Very few studies have focused on the soil environmental changes induced by other external conditions, such as geological processes and anthropogenic activity. To systematically illustrate the soil fissure, according to the characteristics of soil cracks, and considering the properties of soil preferential flow path, the geneses and the characteristics of soil cracks have been comprehensively analyzed and summarized in this study. Two major types of soil cracks have been proposed: one is the cracks caused by NE and the other is the cracks caused by anthropogenic activity. Additionally, based on the specific differences of these geneses, these two types of soil cracks have been further divided into six subtypes and fourteen sub-subtypes, respectively. In this article, a genetic classification method of soil cracks is systematically proposed, which provides a new approach for the related research of soil cracks.

No abstract